Energy recovery apparatus for a refrigeration system

ABSTRACT

An energy recovery apparatus for use in a refrigeration system, comprises an intake port, a nozzle, a turbine and a discharge port. The intake port is adapted to be in fluid communication with a condenser of a refrigeration system. The nozzle is configured to expand refrigerant discharged from the condenser and increase velocity of the refrigerant as it passes through the nozzle. The turbine is positioned relative to the nozzle and configured to be driven by refrigerant discharged from the nozzle. The discharge port is downstream of the turbine and is configured to be in fluid communication with an evaporator of the refrigeration system.

This patent application is a continuation of U.S. patent applicationSer. No. 13/788,673, filed Mar. 7, 2013, now U.S. Pat. No. 8,716,879which is a continuation of PCT patent application numberPCT/US2011/53500, which was filed on Sep. 27, 2011, which claims thebenefit of provisional patent application No. 61/387,574 filed Sep. 29,2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a refrigeration system and morespecifically to the expansion valve of the refrigeration system thatcontrols the expansion of the refrigerant between the condenser and theevaporator coils of the system.

2. Description of the Related Art

In a conventional refrigeration system, a liquid refrigerant iscirculated through the system and absorbs and removes heat from aninternal environment that is cooled by the system and then rejects thatabsorbed heat in a separate external environment.

FIG. 1 is a temperature (T) versus entropy (S) diagram of a conventionalrefrigeration cycle. In the conventional refrigeration cycle,refrigerant vapor enters the compressor at point 1 and is compressed toan elevated pressure at point 2. The refrigerant then travels throughthe condenser coil nearly at constant pressure from point 2 to point 3.At point 3, the elevated pressure of the refrigerant has a saturationtemperature that is well above the ambient temperature of the externalenvironment. As the refrigerant passes through the condenser coil therefrigerant vapor is condensed into a liquid. From point 3 to point 4the liquid refrigerant is cooled further by about 10 degrees F. belowthe saturation temperature. After the condenser, from point 4 to point5, the liquid refrigerant passes through an expansion valve and theliquid refrigerant is lowered in pressure to a liquid-vapor state, withthe majority of the refrigerant being liquid. The expansion valve in theconventional refrigeration cycle is essentially an orifice. The decreasein pressure of the refrigerant is a constant enthalpy process. Entropyincreases due to the mixing friction that occurs in the standardexpansion valve. The cold refrigerant then passes through the evaporatorcoils from point 5 to point 1. A fan circulates the warm air of theinternal environment across the evaporator coils and the coils gatherthe heat from the circulated air of the internal environment. Therefrigerant vapor then returns to the compressor at point 1 to completethe refrigeration cycle.

FIG. 2 is a schematic representation of a standard refrigeration system.The standard system shown in FIG. 2 has four basic components: acompressor 6, a condenser 7, an expansion valve (also called a throttlevalve) 8, and an evaporator 9. The system also typically includes anexternal fan 10 and an internal fan 11.

In the operation of the refrigeration system, the circulatingrefrigerant enters the compressor 6 as a vapor and is compressed to ahigh pressure, resulting in a higher temperature of the refrigerant. Thehot, compressed vapor is then in the thermodynamic state known as asuper-heated vapor. At this temperature and pressure, the refrigerantcan be condensed with typically available ambient cooling air from theexternal environment of the refrigeration system.

The hot vapor is passed through the condenser where it is cooled in thecondenser coils and condenses into a liquid. The external fan 10 movesthe ambient air of the external environment across the condenser coils.The heat of the refrigerant passing through the condenser coils passesfrom the coils to the air circulated through the coils by the fan 10. Asthe heat of the refrigerant passes from the condenser coils into thecirculating air, the refrigerant condenses to a liquid.

The liquid refrigerant then passes through the expansion valve 8 wherethe liquid undergoes an abrupt reduction in pressure which causes partof the liquid refrigerant to evaporate to a vapor. The evaporationlowers the temperature of the liquid and vapor refrigerant to atemperature that is colder than the temperature of the internalenvironment of the refrigeration system that is being cooled.

The cold liquid and vapor refrigerant are then routed through theevaporator coils. The internal fan 11 circulates the warm air of theinternal environment across the coils of the evaporator 9. The warm airof the internal environment circulated by the fan 11 through the coilsof the evaporator 9 evaporates the liquid part of the cold refrigerantmixture passing through the coils of the evaporator 9. Simultaneously,the circulating air passed through the coils of the evaporator 9 iscooled and lowers the temperature of the internal environment.

The refrigerant vapor exiting the coils of the evaporator 9 is routedback to the compressor 6 to complete the refrigeration cycle.

Air conditioning designers have for years increased the efficiency ofthe standard refrigeration cycle described above by several means. Someexamples of those that have been successful include:

-   -   Use of “scroll” compressors that are more efficient than screw        or piston-type compressors.    -   Use of high efficiency compressor motors such as electrically        commutated permanent magnet motors.    -   Use of oversize condenser coils that lower the condenser        pressure required.    -   Use of oversize evaporator coils that raise the evaporator        pressure required.    -   Use of modulating systems that run part of the time at reduced        load to increase overall cycle efficiency.    -   Use of high efficiency blower housings and blower motors to        reduce the non-compressor electrical usage.

However, even with these substantial improvements, obtaining a higherseasonal energy efficiency ratio (SEER) ratings are desired togetherwith less expensive refrigeration systems that do not involve expensiveoversize copper and aluminum heat exchangers.

One area where there have been attempts in improving the efficiency insub-critical point refrigeration cycles is in harnessing the expansionenergy that is normally lost across the expansion valve. A theoreticalsub-critical point refrigeration cycle that would accomplish this wouldhave a TS diagram such as that shown in FIG. 3.

A theoretical refrigeration system that would produce a TS diagram suchas that shown in FIG. 3 is shown schematically in FIG. 4.

The refrigeration cycle shown in FIG. 4 is substantially the same as thestandard refrigeration cycle discussed earlier and shown in FIG. 2,except that in the refrigeration cycle of FIG. 4, the uncontrolledexpansion of the refrigerant that occurs at the expansion valve isinstead a controlled expansion with the resultant expansion event beingcloser to an isentropic event instead of an adiabatic event. The endresult of the refrigeration cycle shown in FIG. 4 is that work can beremoved from the controlled expansion, and additional refrigerationcapacity can be used which is equal to the energy that was removed.

There have been attempts to duplicate the refrigeration cycle shown inFIG. 4 in the past, but for different reasons they were not successful.

U.S. Pat. No. 3,934,424 discloses an attempt at duplicating therefrigeration cycle shown in FIG. 4. However, the requirement of asecond compressor that was mechanically coupled to the expansion valveadded complexity to the attempt.

U.S. Pat. No. 5,819,554 also discloses an attempt at duplicating therefrigeration cycle of FIG. 4. However, requiring the expansion valve tobe directly coupled to the compressor also increased the complexity ofthis attempt. In addition, putting the cold expansion refrigerant linesout at the compressor could potentially negatively affect thecommercialization of the system.

U.S. Pat. No. 6,272,871 also discloses another attempt at duplicatingthe refrigeration cycle of FIG. 4 through the use of a positivedisplacement expansion valve. However, this also required a throttlevalve being positioned before the expansion device so that therefrigerant moving through the device had a higher vapor content.

U.S. Pat. No. 6,543,238 also discloses an attempt to duplicate therefrigeration cycle of FIG. 4 by using a supercritical point vaporcompression refrigerant cycle. This attempt employed a scroll expander,similar to a scroll compressor to expand the supercritical refrigerant.Being a supercritical point cycle, the refrigerant is neverincompressible, and therefore easier to manage through the energyrecovery system. This system appears practical for very largecommercial-type units, but would likely be too complex and too expensivefor a residential application.

SUMMARY OF THE INVENTION

The present invention overcomes the shortcomings of prior attempts toproduce the refrigeration cycle shown in FIG. 4 by providing a novelenergy recovery apparatus for an air conditioning system.

The energy recovery apparatus includes a nozzle and a turbine. Thenozzle generally emulates an orifice-type expansion valve of the typepresently employed in sub-critical point air conditioning cycles. Thisenables the air conditioning system of the invention to operate in aconventional manner and removes the difficulties in employing andcontrolling a positive displacement expansion valve.

The nozzle of the energy recovery apparatus has a diverging nozzleportion that harvests the energy through the partial phase change of therefrigerant. Without the divergent nozzle the thermodynamic energy thatis available would not be realized in the velocity of the vapor/liquidstream leaving the nozzle. The enthalpy the refrigerant contains canonly be harvested while allowing a phase change. This phase changerequires a zone of controlled expansion, which the diverging nozzleaccomplishes.

The energy recovery apparatus of one embodiment has an internalsynchronous generator that generates electrical power which can bereturned to the single phase 115 V or 230 V power source of the indoorair handler to reduce wattage usage. The power generated for a five tonunit is estimated to be 146 watts, which is substantial. The internalgenerator keeps refrigerant lines from being routed in ways that wouldnot be commercial. The internal generator also eliminates any externalshafts that would have to be refrigerant sealed, which is nearimpossible.

One aspect of the present invention is a subcritical-point refrigerationsystem comprising an evaporator, a compressor, a condenser, and anenergy recovery apparatus. The evaporator comprises an intake port and adischarge port. The evaporator is configured to evaporate a coldrefrigerant from a liquid-vapor state to a vapor state. The compressorcomprises an intake port and a discharge portion. The intake port of thecompressor is in fluid communication with the discharge port of theevaporator. The compressor is configured to receive refrigerantdischarged from the evaporator and compress the refrigerant to anelevated, sub-critical pressure. The condenser comprises an intake portand a discharge port. The intake port of the condenser is in fluidcommunication with the discharge port of the compressor. The condenseris configured to receive refrigerant discharged from the compressor andcondense the refrigerant discharged from the compressor to one of asaturated-liquid state, a liquid state cooler than the saturated-liquidstate, and a liquid-vapor state near the saturated-liquid state. Theenergy recovery apparatus comprises an intake port and a discharge port.The intake port of the energy recovery apparatus is in fluidcommunication with the discharge port of the condenser. The dischargeport of the energy recovery apparatus is in fluid communication with theintake port of the evaporator. The energy recovery apparatus furthercomprises a nozzle and a turbine, the nozzle comprises a throat regionand a diverging portion. The diverging portion is downstream of thethroat region. The throat has a cross-sectional area less than across-sectional area of the intake port of the energy recoveryapparatus. The nozzle is configured to expand refrigerant dischargedfrom the condenser and increase velocity of the refrigerant as it passesthrough the nozzle. The turbine is positioned and configured to bedriven by refrigerant discharged from the nozzle. The discharge port ofthe energy recovery apparatus is downstream of the turbine. Anotheraspect of the present invention is a method of operating such arefrigeration system in a manner that refrigerant enters the nozzle in aliquid state and is discharged from the nozzle in a liquid-vapor state.

Another aspect of the present invention is an energy recovery apparatusfor use in a refrigeration system, in which the refrigeration systemcomprises an evaporator, a compressor and a condenser. The evaporator isconfigured to evaporate a cold refrigerant from a liquid-vapor state toa vapor state. The compressor is configured to receive refrigerantdischarged from the evaporator and compress the refrigerant to anelevated, sub-critical pressure. The condenser is configured to receiverefrigerant discharged from the compressor and condense the refrigerantto one of a saturated-liquid state, a liquid state cooler than thesaturated-liquid state, and a liquid-vapor state near thesaturated-liquid state. The energy recovery apparatus comprises anintake port adapted to be in fluid communication with the condenser, adischarge port adapted to be in fluid communication with the evaporator,a nozzle, and a turbine. The nozzle comprises a throat region and adiverging portion. The diverging portion is downstream of the throatregion. The throat has a cross-sectional area less than across-sectional area of the intake port of the energy recoveryapparatus. The nozzle is configured to expand refrigerant dischargedfrom the condenser and increase velocity of the refrigerant as it passesthrough the nozzle. The turbine is positioned and configured to bedriven by refrigerant discharged from the nozzle. The discharge port ofthe energy recovery apparatus is downstream of the turbine.

Another aspect of the present invention is a method comprising sellingan energy recovery apparatus. The energy recovery apparatus comprises anintake port adapted to be in fluid communication with the condenser, adischarge port adapted to be in fluid communication with the evaporator,a nozzle, and a turbine. The nozzle comprises a throat region and adiverging portion. The diverging portion is downstream of the throatregion. The throat has a cross-sectional area less than across-sectional area of the intake port of the energy recoveryapparatus. The nozzle is configured to expand refrigerant dischargedfrom the condenser and increase velocity of the refrigerant as it passesthrough the nozzle. The turbine is positioned and configured to bedriven by refrigerant discharged from the nozzle. The discharge port ofthe energy recovery apparatus is downstream of the turbine. The energyrecovery apparatus further comprises a generator coupled to the turbineand driven by the turbine. The generator is configured to produceelectricity as a result of the turbine being driven by refrigerantdischarged from the nozzle. The energy recovery apparatus furthercomprises a housing encompassing the turbine and the generator. Themethod further comprises including with the energy recovery apparatusindicia (e.g., instructions, explanation, etc.) that the energy recoveryapparatus is to be placed in fluid communication with an evaporator of arefrigeration system.

In one embodiment, the turbine of the energy recovery apparatus is aunique two-stage turbine that has only a single rotating element. Thestraightening veins of the turbine are part of the turbine housing,providing a unique cost-efficient structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a temperature (T) versus entropy (S) diagram of a conventionalrefrigeration cycle.

FIG. 2 is schematic representation of a standard refrigeration system.

FIG. 3 is a temperature (T) versus entropy (S) diagram of a sub-criticalrefrigeration cycle.

FIG. 4 is a schematic representation of a refrigeration system thatwould produce the TS diagram of FIG. 3.

FIG. 5 is a side-sectioned view of an energy recovery apparatus of theinvention.

FIG. 6 is a top plan view of the energy recovery apparatus in a planealong the line 6-6 of FIG. 5.

FIG. 7 is a perspective view of the energy recovery apparatus as shownin FIG. 6.

FIG. 8 is a perspective view of the energy recovery apparatus as shownin FIG. 5.

FIG. 9 is a perspective view of the exterior of the energy recoveryapparatus of FIG. 5.

FIG. 10 is a perspective, sectioned view of the generator core of theenergy recovery apparatus in the plane of line 10-10 of FIG. 5.

FIG. 11 is a perspective view of a second embodiment of an energyrecovery apparatus of the present invention;

FIG. 12 is a perspective view of the energy recovery apparatus of FIG.11 with a cover part of a housing of the energy recovery apparatusremoved to show a turbine and a nozzle;

FIG. 13 is a top plan view of the energy recovery apparatus of FIG. 12;

FIG. 14 is a side elevational view of the energy recovery apparatus ofFIG. 12;

FIG. 15 is a side elevational view of the energy recovery apparatus ofFIG. 11 with portions broken away to show details.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 5 is a cross-section view of a first embodiment of an energyrecovery apparatus 14 of the invention. The energy recovery apparatus 14is basically comprised of a housing 16 containing a turbine 18 and agenerator 20.

The housing 16 is comprised of three parts. A first, center housing part22 has an interior that supports a bearing assembly 24. The center part22 is attached to a second, side wall part 26 of the housing.

The side wall 26 extends around an interior volume of the housing 16.The side wall 26 also includes a hollow center column 28. The interiorof the center column 28 supports a second bearing assembly 30.

A third, cover part of the housing 32 is attached to the top of the sidewall 26. The cover part 32 encloses the hollow interior of the housing16. The cover part 32 has a center, cylindrical outlet opening 34 thatis the outlet for the refrigerant passing through the expansion energyrecovery apparatus 14. An interior surface of the cover part 32 isformed with integral, stationary turbine blades 36 that function as thecenter row of blades of the turbine 18 to be described. Referring toFIGS. 6-9, the housing cover part 32 is also formed with a refrigerantinlet opening 38. This is the inlet for the refrigerant entering theexpansion energy recovery apparatus 14. FIGS. 6 and 7 show the housingcover part 32 having a nozzle insert 40 just inside the inlet opening38. The nozzle insert 40 is formed with a diverging exit area 42 thatopens into the interior of the housing 16 and in particular the interiorof the housing cover part 32.

The turbine 18 includes a center shaft 36 mounted for rotation in thetwo bearing assemblies 24, 30. As shown in FIGS. 5-8, a turbine disk 48is mounted on the top of the turbine shaft 46 for rotation with theshaft. The turbine 18 is a two-stage turbine that is comprised of afirst, inner row of blades 50 and a second, outer row of blades thatproject upwardly from the turbine disk 48 as shown in FIGS. 5-8. FIGS. 6and 7 show the blade orientation of the turbine 18. The center row ofblades 36 are the straightening blades of the two-stage turbine. Thiscenter row of blades 36 is stationary relative to the turbine disk 48and the inner row of blades 50 and the outer row of blades 52.Refrigerant entering the housing 16 through the nozzle insert 40 passesthrough the outer blades 52 on the turbine disk 48, then through thecenter turbine blades 46 on the housing cover 32, then through the innerblades 50 on the turbine disk 48 before exiting the housing 16 throughthe outlet opening 34 of the cover part 32. The bottom surface of theturbine disk 48 opposite the inner blades 50 and outer blades 52 has acylindrical wall 54 attached thereto. The cylindrical wall 54 is therotor backing that supports four permanent magnets 56 as shown in FIGS.5, 8 and 10. The cylindrical wall 54 of the turbine and the fourpermanent magnets 56 form the outside rotor of the generator 20.

Referring to FIGS. 5, 8 and 10, the generator 20 is preferably a fourpole generator comprised of a stack of stator plates 58 and four statorwindings 60. The stack of stator plates 58 is secured stationary on thecenter column 28 of the housing side wall 26. FIG. 10 shows the relativepositions of the stack of stator plates 58, the stator windings 60 andthe permanent magnets 56 of the generator 20.

In operation of the energy recovery apparatus 14 of the invention in arefrigerant system (e.g., an air conditioning system) such as that shownin FIG. 4, entry of refrigerant into the valve housing 16 through thenozzle insert 40 results in a counter-clockwise rotation of the turbineinner blades 50 and outer blades 52 relative to the stationary center,straightening blades 36. As the refrigerant passes between the blades,the refrigerant exits the housing through the housing outlet opening 34.

The refrigerant passing through the housing 16 causes rotation of theturbine disk 48 and the turbine shaft 46, which also causes rotation ofthe permanent magnets 56 on the cylindrical wall 54 which form the rotorof the generator 20. The rotation of the permanent magnets 56 induces acurrent in the stator windings 60 which produces electricity from theenergy recovery apparatus 14. The electricity produced can be routedback to a fan of the air conditioning system to help power its needs andincrease the air conditioning capacity. This increases the energyefficiency of the air conditioning system and increases the SEER ratingof the air conditioning system.

Another embodiment of an energy recovery apparatus of the presentinvention is indicated generally by reference numeral 114 in FIGS.11-15. In FIG. 11, the energy recovery apparatus 114 is shown having ahousing 116, inlet port (or intake port) 138 configured to be in fluidcommunication with a condenser, and an outlet opening (discharge port)134, configured to be in fluid communication with an evaporator. Inother words, like energy recovery apparatus 14, the energy recoveryapparatus 114 replaces the expansion valve 8 in FIG. 2. The energyrecovery apparatus 114 is similar to the energy recovery apparatus 14,except for the differences set forth herein.

The energy recovery apparatus 114 includes a turbine 118. The turbine118 comprises a radial flow turbine having a turbine wheel 118 arotatable about a turbine axis X (see FIG. 15) with only one row ofturbine blades 152, with each of the turbine blades being radiallyspaced from the turbine axis. The turbine blades 152 are secured to androtate with the turbine wheel. Alternatively, the turbine could be anaxial flow turbine.

The energy recovery apparatus 114 also includes nozzle 142 similar tothe nozzle of the energy recovery apparatus 14, except it is positionedto direct refrigerant from a region radially inward of the row ofturbine blades 152 toward the row of turbine blades 152 such thatrefrigerant passing through the turbine blades flows radially outward.The nozzle 142 and turbine 118 are positioned relative to each othersuch that the turbine is driven by refrigerant discharged from thenozzle. The discharge port of the energy recovery apparatus 114 isdownstream of the turbine.

Referring to FIG. 15, the nozzle 142 comprises a converging portion 142a, a throat region 142 b, and a diverging portion 142 c. The convergingportion 142 a is downstream of the intake port, the throat portion 142 bis downstream of the converging portion, and the diverging portion 142 cis downstream of the throat region. As shown in FIG. 15, the nozzle 142may also include a generally cylindrical tube extending downstream fromthe downstream end of the diverging portion 142 c, and positioned todischarge refrigerant to the turbine 118. Preferably, the ratio of thecross-sectional area of the downstream end of the diverging portion 142c to the cross-sectional area of the throat portion 142 b is between 1.2and 1.4, and is more preferably between about 1.25 and about 1.35. Thenozzle 142 is configured to expand refrigerant discharged from thecondenser and increase velocity of the refrigerant as it passes throughthe nozzle.

The energy recovery apparatus 114 further comprises a generator 120(FIG. 15) coupled to the turbine 118 and driven by the turbine. Thegenerator 120 is similar to the generator 20 of energy recoveryapparatus 14. The generator 120 is configured to produce electricity asa result of the turbine 118 being driven by refrigerant discharged fromthe nozzle. The housing 116 encompasses and contains the turbine 118 andthe generator 120. Preferably, the housing 116 and the turbine 118 arein fluid communication with each other. More preferably, the housing116, the turbine 118 and the generator 120 are arranged and configuredsuch that refrigerant introduced into the housing cools and lubricatesthe generator. The housing 116 is configured such that, during normaloperation, fluid introduced into the housing 116 via the intake port 138escapes from the housing only via the discharge port 134. The turbineand generator are in fluid communication with each other such that atleast some refrigerant directed to the turbine is able to flow to thegenerator. The internal generator also eliminates any external shaftsthat would have to be refrigerant sealed. In other words, the housing116 is preferably devoid of any openings for the passage of externalshafts.

In operation, the intake port 138 of the energy recovery apparatus 114is operatively coupled (e.g., via a refrigerant line) in fluidcommunication to the discharge port of a condenser of a refrigerantsystem such that refrigerant discharged from the condenser flows intothe energy recovery apparatus. Similarly, the discharge port 134 of theenergy recovery apparatus 114 is operatively coupled in fluidcommunication to the intake port of an evaporator such that refrigerantdischarged from the energy recovery apparatus flows into the evaporator.Preferably, the refrigerant system is then operated such thatrefrigerant is discharged from the condenser in a liquid state at atemperature below (e.g., ten degrees F. below) the liquid saturationtemperature for that same pressure. The refrigerant enters the energyrecovery apparatus 114 in a liquid state and is passed through thenozzle 142. The nozzle 142 is shaped and configured such thatrefrigerant enters the converging portion 142 a in a liquid state, isexpanded by the nozzle, and is then discharged from the nozzle in aliquid-vapor state. As such, passing the refrigerant through the nozzle142 causes the refrigerant to decrease in pressure and temperature andexpand from a liquid state to a liquid-vapor state. The refrigerant isdischarged from the nozzle 142 at a low temperature, high velocityliquid-vapor and toward the blades 152 of the turbine 118 to cause theturbine to rotate about the turbine axis X, which also causes rotationof the permanent magnets on the cylindrical wall which form the rotor ofthe generator 120. The rotation of the permanent magnets induces acurrent in the stator windings of the generator to thereby produceelectricity. The refrigerant then flows through the turbine 118 and isdischarged out the discharge port 134 of the energy recovery apparatus114 and conveyed to the evaporator.

The energy recovery apparatus of the present invention may be sold ordistributed as part of a complete refrigerant system or as a separateunit to be added to a refrigerant system (e.g., to replace an expansionvalve of an existing refrigeration system). In connection with the saleor distribution of the energy recovery apparatus, a user (e.g., apurchaser of the energy recovery apparatus) is instructed that thepurpose of the energy recovery apparatus is to expand refrigerant in arefrigerant system be placed in fluid communication of the energyrecovery apparatus is sold or distributed as a separate unit. The useris then induced to have the energy recovery apparatus placed in fluidcommunication with a condenser and evaporator of a refrigeration system.

As various modifications could be made in the constructions and methodsherein described and illustrated without departing from the scope of theinvention, it is intended that all matter contained in the foregoingdescription or shown in the accompanying drawings shall be interpretedas illustrative rather than limiting. Thus, the breadth and scope of thepresent invention should not be limited by any of the above-describedexemplary embodiments, but should be defined only in accordance with thefollowing claims appended hereto and their equivalents.

It should also be understood that when introducing elements of thepresent invention in the claims or in the above description of exemplaryembodiments of the invention, the terms “comprising,” “including,” and“having” are intended to be open-ended and mean that there may beadditional elements other than the listed elements. Additionally, theterm “portion” should be construed as meaning some or all of the item orelement that it qualifies. Moreover, use of identifiers such as first,second, and third should not be construed in a manner imposing anyrelative position or time sequence between limitations. Still further,the order in which the steps of any method claim that follows arepresented should not be construed in a manner limiting the order inwhich such steps must be performed.

What is claimed is:
 1. A refrigeration system comprising: an evaporatorcomprising an intake port and a discharge port, the evaporator beingconfigured to evaporate a cold refrigerant from a liquid-vapor state toa vapor state; a compressor comprising an intake port and a dischargeportion, the intake port of the compressor being in fluid communicationwith the discharge port of the evaporator, the compressor beingconfigured to receive refrigerant discharged from the evaporator andcompress the refrigerant to an elevated, sub-critical pressure; acondenser comprising an intake port and a discharge port, the intakeport of the condenser being in fluid communication with the dischargeport of the compressor, the condenser being configured to receiverefrigerant discharged from the compressor and condense the refrigerantdischarged from the compressor to one of a saturated-liquid state, aliquid state cooler than the saturated-liquid state, and a liquid-vaporstate near the saturated-liquid state; an energy recovery apparatuscomprising an intake port and a discharge port, the intake port of theenergy recovery apparatus being in fluid communication with thedischarge port of the condenser, the discharge port of the energyrecovery apparatus being in fluid communication with the intake port ofthe evaporator, the energy recovery apparatus further comprising anozzle, a turbine, and a generator, the nozzle being configured toexpand refrigerant discharged from the condenser and increase velocityof the refrigerant as it passes through the nozzle, the turbine beingpositioned and configured to be driven by refrigerant discharged fromthe nozzle, the discharge port of the energy recovery apparatus beingdownstream of the turbine, the generator being coupled to the turbineand driven by the turbine, the generator being configured to produceelectricity as a result of the turbine being driven by refrigerantdischarged from the nozzle.
 2. A refrigeration system as set forth inclaim 1 wherein the energy recovery apparatus further comprising ahousing encompassing the turbine and the generator.
 3. A methodcomprising operating a refrigerant system as set forth in claim 1 in amanner such that refrigerant enters the nozzle in a liquid state and isdischarged from the nozzle in a liquid-vapor state.
 4. An energyrecovery apparatus for use in a refrigeration system, the refrigerationsystem comprising an evaporator, a compressor and a condenser, theevaporator being configured to evaporate a cold refrigerant from aliquid-vapor state to a vapor state, the compressor being configured toreceive refrigerant discharged from the evaporator and compress therefrigerant to an elevated, sub-critical pressure, the condenser beingconfigured to receive refrigerant discharged from the compressor andcondense the refrigerant to one of a saturated-liquid state, a liquidstate cooler than the saturated-liquid state, and a liquid-vapor statenear the saturated-liquid state, the energy recovery apparatuscomprising: an intake port adapted to be in fluid communication with thecondenser; a discharge port adapted to be in fluid communication withthe evaporator; a nozzle adapted and configured to expand refrigerantdischarged from the condenser and increase velocity of the refrigerantas it passes through the nozzle; and a turbine positioned relative tothe nozzle and configured to be driven by refrigerant discharged fromthe nozzle, the discharge port of the energy recovery apparatus beingdownstream of the turbine; and a generator coupled to the turbine andconfigured to be driven by the turbine, the generator being configuredto produce electricity as a result of the turbine being driven byrefrigerant discharged from the nozzle.
 5. An energy recovery apparatusas set forth in claim 4 wherein the nozzle is shaped and configured suchthat refrigerant entering the nozzle in a liquid state is expanded bythe nozzle and discharged from the nozzle in a liquid-vapor state.
 6. Anenergy recovery apparatus as set forth in claim 4 wherein the turbinecomprises a radial flow turbine having a turbine wheel rotatable about aturbine axis and at least one row of turbine blades with each turbineblade of said at least one row of turbine blades being radially spacedfrom the turbine axis, the turbine blades of said at least one row ofturbine blades being configured to rotate with the turbine wheel.
 7. Anenergy recovery apparatus as set forth in claim 6 wherein the nozzle andturbine are arranged and positioned relative to each other in a mannersuch that refrigerant discharged from the nozzle is discharged in aregion radially inward of and toward said at least one row of turbineblades.
 8. An energy recovery apparatus as set forth in claim 7 whereinthe turbine includes only one row of turbine blades.
 9. An energyrecovery apparatus as set forth in claim 6 wherein said at least one rowof turbine blades comprises a plurality of rows of turbine blades. 10.An energy recovery apparatus as set forth in claim 9 further comprisingat least one stationary row of turbine blades.
 11. An energy recoveryapparatus as set forth in claim 6 wherein said turbine comprises amulti-stage turbine.
 12. An energy recovery apparatus as set forth inclaim 6 wherein the nozzle and turbine are arranged and positionedrelative to each other in a manner such that refrigerant discharged fromthe nozzle is discharged in a region radially outward of and toward saidat least one row of turbine blades.
 13. A method comprising operativelycoupling the discharge port of an energy recovery apparatus as set forthin claim 4 to an evaporator of a refrigeration system such that thedischarge port of the energy recovery apparatus is in fluidcommunication with the evaporator.
 14. A method comprising instructing auser to place an energy recovery apparatus as set forth in claim 4 influid communication with an evaporator of a refrigeration system.
 15. Amethod comprising selling an energy recovery apparatus as set forth inclaim 4 and including with the energy recovery apparatus indicia thatthe energy recovery apparatus is to be placed in fluid communicationwith an evaporator of a refrigeration system.
 16. A method comprisinginstructing a user to place an energy recovery apparatus as set forth inclaim 4 in fluid communication with a refrigeration line of arefrigeration system.
 17. A method comprising inducing a user to placean energy recovery apparatus as set forth in claim 4 in fluidcommunication with a refrigeration line of a refrigeration system.
 18. Amethod comprising inducing a user to place an energy recovery apparatusin fluid communication with a refrigeration line of a refrigerationsystem, the refrigeration system comprising an evaporator, a compressorand a condenser, the evaporator being configured to evaporate a coldrefrigerant from a liquid-vapor state to a vapor state, the compressorbeing configured to receive refrigerant discharged from the evaporatorand compress the refrigerant to an elevated, sub-critical pressure, thecondenser being configured to receive refrigerant discharged from thecompressor and condense the refrigerant to one of a saturated-liquidstate, a liquid state cooler than the saturated-liquid state, and aliquid-vapor state near the saturated-liquid state, the energy recoveryapparatus comprising: an intake port adapted to be in fluidcommunication with the condenser; a discharge port adapted to be influid communication with the evaporator; a nozzle adapted and configuredto expand refrigerant discharged from the condenser and increasevelocity of the refrigerant as it passes through the nozzle; and aturbine positioned relative to the nozzle and configured to be driven byrefrigerant discharged from the nozzle, the discharge port of the energyrecovery apparatus being downstream of the turbine; and a generatorcoupled to the turbine and configured to be driven by the turbine, thegenerator being configured to produce electricity as a result of theturbine being driven by refrigerant discharged from the nozzle.